Jason made his AFL debut for the Sydney Swans in Round 1, 1998 against Port Adelaide. He had a consistent debut season in 1998 and was nominated for the Norwich Rising Star award that year. He kicked 4 goals against the Kangaroos in Round 4 of 2004 in one of his best matches of his career, and was noted as a consistent rebounding backman with a strong mark. However, a serious knee injury in Round 10, 2004 against the Western Bulldogs interrupted his career and the very slow process of recovery resulted in Jason being traded to the Carlton Football Club at the end of the 2005 season. He played 142 games in eight seasons at the Swans.
Carlton
Saddington debuted for Carlton against his old club, the Sydney Swans, in Round 3, 2006. He played six consecutive games, scoring two goals, before his season was again ended by the recurring knee injury. It was at this late stage that Saddington was told for the first time that the medical staff at Sydney Swans were aware of complications that had resulted from his first knee injury and had withheld this information from him and also from his new club. He had a further operation, and missed the rest of the 2006 season. Fully recovered, Saddington played very good football for Carlton's, the Northern Bullants, in the early rounds of season 2007 and played his first senior game of the 2007 AFL Season at the MCG against Magpies in Round 7 on Saturday 12 May 2007 taking a team high total of 12 marks. He played his 150th AFL game against the Kangaroos at Carrara Stadium on the Gold Coast the following week. With the replacement of coach Denis Pagan with Brett Ratten, Saddington spent more time as a part-time forward later in the season. Saddington played only two games for Carlton in 2008, both late in the season. He won the Northern Bullants' best and fairest award, the Laurie Hill Trophy, for his strong season at VFL level during the season. Jason was offered a position in an AFL initiative to assist homeless people.
Post-AFL career
Saddington officially retired from the AFL on 13 October 2008. He continued to play on with the Northern Bullants as a VFL-listed player in 2009, where he was a part of the club's losing grand final team. In 2012, Saddington played for the Balmain Dockers in the Sydney AFL competition alongside premiership players Nick Davis and Chad Fletcher. In 2014, Saddington coached the NSW/ACT Rams and was named Coach of the 2014 NAB AFL U18 All Australian Team. On 23 October 2014 Saddington was announced as new Academy Coach by the AFL.
